3.33 The probability of getting n heads in a row when tossing a fair coin n time

Question

3.33 The probability of getting n heads in a row when tossing a fair coin n times is 2n. Implement function prob() that takes a nonnegative integer n as input and returns the probability of n heads in a row when tossing a fair coin n times. >>> prob(1) 0.5 >>> prob(2) 0.25

3.34 Implement function reverse_int() that takes a three-digit integer as input and returns the integer obtained by reversing its digits. For example, if the input is 123, your function should return 321. You are not allowed to use the string data type operations to do this task. Your program should simply read the input as an integer and process it as an integer using operators such as // and %. You may assume that the input integer does not end with the 0 digit. >>> reverse_int(123) 321 >>> reverse_int(908) 809

3.36 Implement function abbreviation() that takes a day of the week as input and returns its two-letter abbreviation. >>> abbreviation('Tuesday') 'Tu'

Explanation / Answer

Solution 3.33

// function is c++ syntax

// include math.h in header

double prob(int n) {
   return pow(0.5, n);
}

Solution 3.34

// c++ code

int reverse_int(int num) {
   int rev = 0;
   int temp;
  
   temp = num%10;
   rev += temp;
   rev *= 10;
  
   num /= 10;
   temp = num%10;
   rev += temp;
   rev *= 10;
  
   num /= 10;
   rev += num;
  
   return rev;
}

Solution 3.36

// c++ code

string abbreviation(string day) {
   string ans;
  
   if (day == "Sunday")
       ans = "Su";
   if (day == "Monday")
       ans = "Mo";
   if (day == "Tuesday")
       ans = "Tu";
   if (day == "Wednesday")
       ans = "We";
   if (day == "Thursday")
       ans = "Th";
   if (day == "Friday")
       ans = "Fr";
   if (day == "Saturday")
       ans = "Sa";
      
   return ans;                      
}

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